1. Field of the Invention
The present invention relates to a thermoelectric conversion device, and particularly to a thermoelectric conversion device having a stacked structure.
2. Description of Related Art
Development of technology of renewable energy has become an important issue due to problems of energy shortages. Taking automobiles as an example, waste heat of the engine accounts for one-third of power of the automobile; if the waste heat of gas emission is provided for electricity generation from thermoelectric conversion, consumption of fuel is reduced. In addition, factories and households emit large amounts of waste heat, and how to recycle and reuse the waste heat is an important issue. However, currently most waste heat does not have adequate recycling technology, so that waste of energy is caused.
Thermoelectric conversion technology has been one of key technologies of industrial research and development. A working principle of the thermoelectric conversion technology is linking an N type semiconductor material and a P type semiconductor material into a thermoelectric couple; by utilizing two ends of the N type and P type semiconductor material contacting different temperatures, energy transfer is generated and electric currents are generated in the thermoelectric couple. The above is called the Seebeck effect. Electricity generation by the thermoelectric conversion mainly uses temperature differences between the two ends of the N type and P type semiconductor materials to make the thermoelectric couple generate the electric currents, so that the electricity generation by the thermoelectric conversion does not cause pollution to the environment, and reaction speeds of the electricity generation by the thermoelectric conversion are fast. The electricity generation by the thermoelectric conversion may be further combined with technology of recycling the waste heat, thereby using the waste heat as a heat source for the electricity generation by the thermoelectric conversion and reducing waste of energy. In addition, a plurality of thermoelectric couples may be electrically and serially connected and stacked to form a thermoelectric conversion device, so as to comply with different requirements of electricity generation capacity. From another point of view, the thermoelectric conversion device directly converts heat into electricity and not through moving parts such as engine pistons, so that reliability of a structure of the thermoelectric conversion device is enhanced. Production of the thermoelectric conversion device may be combined with micro electromechanical and semiconductor processes, thereby largely reducing a volume of the thermoelectric conversion device.
However, the largest problem in application of the electricity generation by the thermoelectric conversion is the poor efficiency of the thermoelectric conversion. In order to enhance the efficiency of thermoelectric conversion of the thermoelectric device, thermoelectric material having superb thermoelectric characteristics may be developed through research and development of material technologies. In addition, since currently an assembly density of the thermoelectric conversion device is limited, electricity generation capacity by the thermoelectric conversion device is limited. Hence, another important technological direction of enhancing the efficiency of the thermoelectric conversion is improving a design of the structure of the thermoelectric conversion device and enhancing the assembly density of the thermoelectric conversion device, so as to improve the efficacy of the electricity generation by the thermoelectric conversion device.